suboptimal seek_{data,hole} extents traversial

I had deja vu today when I stumbled across the problem that 14516bb7bb6ffbd49f35389f9ece3b2045ba5815 tried to fix (and subsequently got reverted in ad7fefb109b0418bb4f16fc1176fd082f986698b

Dmitry, did you ever get anywhere figuring out how that broke ext3 ?

Dave